The present invention relates to a method for the vapor phase oxidation of a butene to produce acetic acid and to catalysts therefor.
Numerous catalysts, especially vanadium-containing catalysts, are known in the prior art for the oxidation of a butene to produce acetic acid. Among those disclosed in the prior art are mixed oxides of vanadium and titanium, tin, aluminum, or antimony as disclosed in U.S. Pat. No. 3,917,682 issued Nov. 4, 1975 to Tetsuo Mizukami, et al. Japanese Pat. No. 45-31165 published Oct. 8, 1970 discloses butene oxidation catalysts comprising mixed oxides of vanadium and cerium or cadmium, and wherein phosphorous, boron or arsenic may optionally be present. U.S. Pat. No. 3,704,317 issued Nov. 28, 1972 to Takashi Yamashita, et al, discloses a catalyst whose effective elements are vanadium and one or more elements selected from the group consisting of lithium, boron, silicon, chromium, iron, nickel, zinc, zirconium, niobium, ruthenium, rhodium, palladium, tantalum and bismuth. German Offenlegungsschrift No. 2041073 discloses mixed oxide catalysts wherein there is present vanadium plus at least one of antimony and titanium, and at least one of tin, iron, manganese, nickel or copper, and optionally molybdenum and/or tungsten. German Offenlegungsschrift No. 2354425 discloses that a mixed oxide of vanadium and zinc is an effective catalyst, and that a mixed oxide of vanadium and zirconium is an effective catalyst, and also discloses various other metal oxide catalysts.
French Pat. No. 2,092,544 discloses a mixed oxide catalyst containing vanadium and one or more of tin, antimony, titanium and aluminum. Chemical Abstracts, Vol. 74, Pages 316-317, Note 41924a, discloses that Japanese Pat. No. 79-30,802 discloses that mixed oxide catalysts containing vanadium together with iron, nickel or cobalt, and optionally, in addition, phosphorous, boron or arsenic, are useful for butene oxidation. In addition to the foregoing, there are numerous other prior art references to the use of mixed oxides of vanadium with one or more other various metals and to the methods of preparing such catalysts.
Since there has been a great amount of research into suitable catalysts for the vapor phase oxidation of butene to acetic acid, particularly vanadium-containing catalysts, the prior art catalysts give relatively good results. However, in view of the importance of the process and in view of the fact that even small increases in efficiency will make a big difference in the economics of a process, research is constantly under way in order to find new and better catalysts for the vapor phase oxidation of a butene, alone or in mixture with other butenes, to produce acetic acid.
It is thus an object of the present invention to provide a new and useful process for the vapor phase oxidation of butenes to acetic acid. It is another object of the present invention to provide a unique catalyst composition for such purposes. A still further object of the present invention is to provide a process, and catalyst therefor, for the vapor phase oxidation of butenes to acetic acid which provide improved selectivity. Additional objects of the present invention will be apparent from the following description.